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How to Upgrade to High Energy Ignition (HEI)

If you want to upgrade your DeLorean to those same standards, here's how to do it.

Three things are necessary for HEI:
1) Suitable coil (Bosch blue coil is not suitable)
2) Increased voltage into the coil
3) Widened spark plug gap
If you omit any of these three requirements you won't have HEI (or at least not for long in the case of a Bosch blue coil).

Remember that coil voltage rating is only its potential output. Without Steps 2 and 3 the coil will continue to produce lower secondary ignition voltages despite its potential to do better. Simply throwing an HEI coil on the car alone does *NOT* produce HEI.

Do *NOT* use the coil label to position and wire the coil -- use the "+" and "-" markings on top:

This means your label may well end up facing the firewall, as mine does. If you position and wire the coil by the label alone, you may end up wiring the coil backwards. I have had to correct this error on other owners' cars. Bosch blue coils often are marked with numbers instead of polarity signs, which has confused owners. In such instance "15" is positive and "1" is negative.

*** Do not do this unless you have upgraded to an HEI coil. Bosch blue coils can not handle increased voltage ***

There are three ways to increase voltage into the coil using the stock resistor grid:
1) Use one resistor (yields about 11.5 volts into the coil)
2) Use both resistors in parallel (yields about 12.5 volts into the coil)
3) Bypass the resistor grid altogether (yields about 13.5 volts into the coil)

Spark plug gaps act as a voltage regulator. As soon as a spark jumps its gap, that is the maximum amount of voltage the coil will discharge. Even if you have an HEI coil and increased voltage into it, if spark plug gaps are too small, secondary ignition voltages will remain low.

That's it. The only new components necessary for HEI are a suitable coil and a crimp on electrical terminal or two. The stock ignition ECU can drive HEI no problem. I ran one for about half a decade, and quite a few owners are still running one to this day. Ignition ECU can be swapped out of course, but that is optional, not mandatory.

It has a few additional whistles and bells, such as a fuse link into the circuit (original circuit is unprotected, despite the fact that almost the entire car is grounded through the metal bracket that holds the coil...) and real wire plug wires, but those are optional, not mandatory. I also am running a Ford ignition module, simply because a DeLorean runs better as its ratio of Ford components increases:

Hall effect sensor in the distributor never sees secondary voltage. All it does is return a signal from the ignition ECU (ECU never sees secondary voltage either -- only coil input voltage). Only change is from the coil south. ECU wiring is a totally different circuit (except for grounding the coil of course).